This invention relates generally to turbine engines and, more particularly, to a turbine engine having a variable area fan nozzle and a thrust reverser.
It is known to provide an aircraft turbine engine with a series of movable cowls, the positions of which can be adjusted using appropriate actuators. In operation, a bypass airflow flows through a passage between a housing surrounding the turbine (or “core”) and exits from the engine through a fan nozzle. A majority of propulsion thrust is provided by this bypass airflow passing through the fan nozzle. Some turbine engines include a variable area fan nozzle (VAFN) which allows the nozzle size to be adjusted by movement of the cowls. The nozzle dimension is the size of the exit throat defined between the exit end of the fan cowl and the core engine housing (e.g., the turbine). It has been found to be advantageous for the nozzle dimension to be relatively large during take-off and climb phases of engine operation, and to be reduced during cruise conditions. During descent, the nozzle dimension is often increased in case it is necessary to abort landing and enter another climb phase.
When an aircraft lands, the landing gear brakes and imposed aerodynamic drag loads (e.g. flaps, spoilers, etc.) of the aircraft may not be sufficient to slow the aircraft down in the required distance. Thus, most aircraft engines also include thrust reversers to enhance the stopping power of the aircraft. When deployed, thrust reversers redirect the rearward thrust of the engine forward, thereby decelerating the aircraft. The thrust reverser system of an aircraft engine includes a series of cowls positioned on either side of the engine and movable between a stowed and a deployed, operative position. Each cowl is guided for movement along a pair of guide tracks and is driven by a thrust reverser actuator system (TRAS) including a linearly extendable actuator. During deployment, actuators drive the cowl from its stowed position towards a deployed position. Thrust reversers are generally only used for thrust reversal during landing and provide no other additional functionality.
Prior aircraft applications provided separate actuators to drive the VAFN cowls and the thrust reverser cowls and both actuators were grounded to the aircraft structure. The arrangement of a separate actuator for each set of cowls results in the VAFN actuator having a very large stroke which has significant cost, power, and weight implications.